The present invention relates to a carburetor for a marine engine and more particularly to a single adjustment that controls and adjusts the idle speed and also permits positioning of the throttle cam follower relative to the throttle cam.
Many marine engines utilize a carburetor of the type in which the pivotal movement of a throttle plate mounted on a throttle shaft is controlled by the movement of a throttle lever that is engaged by a cam follower moving along the contoured surface of an operator actuated throttle cam. Carburetors of this type require a number of adjustments in order to operate properly. One such adjustment is the idle speed adjustment in which the throttle plate is moved to a slightly open position to allow a flow of an air/fuel mixture during idle operation. Another such adjustment is the positioning of the cam follower relative to the throttle cam in order to take up any clearances between these two members.
Typically these adjustments were made independently of each other and with separate devices provided on the carburetor. The idle speed adjustment was accomplished by rotating an adjustment screw threaded into the carburetor body which would in turn open the throttle plate. The cam follower adjustment was made by loosening a mounting screw on the cam follower and physically moving the cam follower into engagement with the throttle cam.
The present invention provides a single adjustment located on the throttle lever in the form of a rotatable threaded member. Initial rotation of the threaded member brings the cam follower into engagement with the throttle cam and continued rotation of the threaded member results in a positioning of the throttle plate for an idle speed operation.
Thus the present invention provides a single adjustment for two separate carburetor operations.